Index: linux-2.6.16-rc6-mm2/kernel/irq/manage.c
===================================================================
--- linux-2.6.16-rc6-mm2.orig/kernel/irq/manage.c	2006-03-21 15:41:26.000000000 -0800
+++ linux-2.6.16-rc6-mm2/kernel/irq/manage.c	2006-03-21 15:43:15.000000000 -0800
@@ -204,6 +204,8 @@ int setup_irq(unsigned int irq, struct i
 #if defined(ARCH_HAS_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
 	if (new->flags & SA_PERCPU_IRQ)
 		desc->status |= IRQ_PER_CPU;
+	else
+		BUG_ON(desc->status & IRQ_PER_CPU);
 #endif
 	p = &desc->action;
 	if ((old = *p) != NULL) {